The collapsing mechanism of umbrellas according to a prior art typically has a spring (6), which is located between a second umbrella stretcher (2) and an umbrella strut (4). When the umbrella is collapsed, the retracting force of the spring (6) pulls back umbrella stretchers and ribs. A conventional mechanism is shown in FIG. 1, in which a spring (6) is attached at one end to the inner end of the second umbrella stretcher (2) and the other end connected to the outer end of an umbrella strut (4) at a point near the joint between a flexible rib (5) and the umbrella strut (4). When the umbrella is collapsed, the retracting force of the spring (6) urges the umbrella strut (4) and the flexible rib (5) to move upwardly. In this way the umbrella stretcher system gets into a collapsed state. Such a conventional design has a drawback that the retracting force of the spring produces a sideward component force, which retards the collapsing motion of stretchers. As a result, the conventional mechanism reveals a reluctant collapsing operation. Besides, the conventional mechanism needs two holes to be formed on the umbrella strut (4) for the attachment of the spring (6) and the flexible rib (5). Such an arrangement weakens the strength of umbrella struts (4) and makes them vulnerable to external forces.
In view of the above drawbacks, the primary object of the invention is to provide a retracting mechanism used in automatic multiple collapsible umbrellas, in which the outer end of a spring and the inner end of a flexible rib are attached to the same hole formed on an umbrella strut. The structure according to the invention can effectively solve the shortcoming of a conventional umbrella stretcher system and achieve an effect of smoothly collapsing umbrellas.
Now the structure and features of the invention will be described in detail with reference to the accompanying drawings.